Electrical relay



May 3,1927.

| o. GRONDAHL ELECTRICAL RELAY Filed Dec. 27. 1921 Thermo -seen 5 ii z've Thar/n0 sensa zz'vz 16 susfaizce.

INVENTOR' 1 413 ATTQRNEY Patented May 3, 1927.

LABS o. enommnn,

OF PITTSBURGH, PENNSYLVANIA, ASS IGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION.

OF PENNSYLVANIA..

' ELECTRICAL RELAY.

Application filed December 27, 1921. Serial No. 525,097.

My invention relates to electrical relays, and particularly to relays which are dependent for their operation on variations in the electrical characteristics of certain substances in response to variations in the temperature to which they are subjected,

I will describe several forms of relays elnbodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view showing in longitudinal cross-section one form of relay embodying my invention, the various parts thereof being located on the outer surface of the supporting bulb. Figure 2 is a fragmental view in cross-section and on an enlarged scale showing a modification of the relay shown in Fig. 1. Fig. 3 is a view similar to Fig. 1 but showing the parts of the relay located within the supporting bulb instead of on the outer surface thereof. 7

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the relay comprises a glass bulb 7 which, as here shown, is cylindrical in form with ends of reduced diameter. These reduced ends are fitted with lamp plugs 8 and 8 of the screw type, each plug comprising, as usual, a shell 1.2 and a button 9 insulated therefrom.

Mounted within the bulb 7 is a heating elenient H, which, as here shown, is in the form of a fine wire filament, the terminals of which are connected with the shell and buttonrespectively of the terminal plug 8. Sur rounding the bulb 7 is an inner tube-shaped electrode 10 of electro-conduetive material so formed as to obstruct only a portion of the heat rays emitted by the heating. ele-, ment H. This electrode may be in the form ,of a perforated metallic tube, such as a id or a metallic auze, or it may be of thins eet metal which as suflicient cross sectional area to carry the secondary current and which at the same time is capable of transmitting a considerable lgortion of the heat emitted by v the filament Surrounding the electrode 10 is an en.- velope E of a substance having the characteristic of varying in electrical resistance in response to temperature variations, and which I will term the thermo-sensitive substance; This substance preferably has a high temperature coeflieient, and as examples, it may e cupricoxide, cuprous oxide, silver selenide, silver sulphide, carborundum paste, alundum cement, a fusion of copper and mica, the; rare earth oxides used in the Nernst filament, and probably .a number of other substances. The thermo-sensitive substance E is enclosed by a second or outer tube-shaped electrode 11, also of eleetro-c0n ductive material. The inner electrode 10 is electrically connected with the button 9 of plug 8 by a wire 13, and the outer electrode 5 11 is connected by a wire 14 with the-shell 12 of the same plug.

When the inner electrode 10 is in the form of a perforated conductor, such as gauze or a grid, this electrode will not be in electrical contact with all points on the inner surface of the thermo-sensitive substance E, and so the etliciency of the relay willfnot be maximum. If desirable, the etficiency may be increased by a tructure such as that shown in. Fig. 2, w erein a tube-like member 15- of heat-conductive, eleetro-conductive material, such as thin gold leaf, is inter-' posed between the electrode 10 and the thermo-sensitive substance E. This tube or sleeve 15., which may be termed an auxiliary inner electrode, will in effect place the main inner electrode 10 in electrical contact with substantially the entire inner surface of the substance E, and so will increase the efliciency of the relay to a maximum.

I have found that when certain thermosensitive substances are operated in air, a gradual change occurs in the nature of the substance and so in its characteristics. For example, cuprous oxide gradually changes to ctipric oxide, with the result that a change occurs in the characteristics of a relay in which this substance is employed. This change may be avoided by operating the sub stances in racuo or in a gas having no effect on the substance. In Fig. 3 I have shown a relay so constructed'as to permit operation of the thermo-sensitive substance under either of these conditions. In this view, the 100 two electrodes 10 and 11, with the thermo-. sensitive substance E between them, are located within the bulb 7 instead of on the outer surface of the biilb as in Fig. 1. These members may besup orted in any suitable manner, as for examp e by means of loops 16 welded to the bulb. Theheating element H is a wire or filament which passes from button 9 of plug 8, through the inner electrode 10, and returns outside of thebuter electrode 11 to the shell 12 of plug 8. This filament is supported by one or more tie wires 17 which are sealed in the bulb. The bulb 7 may be a receptacle from which the air has been evacuated to a very low pressure, or this bulb may be filled with a gas which has no effect on the thermosensitive substance E, such tor example as nitrogen, argon or helium. A small amount of oxygen may be added to this gas to prevent discharge of oxygen from the tlwrmo-sensitive material E when the relay is first put into service.

It is, oi course. obvious that the inner electrode l and the thermo-sensitive substance E in Fig. 3 may. if desirable. be more intimately connected by an auxiliary inner electrode as in Fig. 9. 7

As a modification of the secondary portion of the relay shown in either Fig. 1 or Fig. 3. the two electrodes 10 and 11 may both be in the form of wire. preferably coils, both embedded in the thermo-sensitivc substance E, the turns of one wire alternating with the turns of the other wire. One end of one wire would then be connected with the shell 12 ot' plug 8, and one end of the other wire would be connected with the button 9 of the same plug. l have not illustrated this modification in the drawings because of the difiiculty of showing the two wire coils embedded in tlmerino-sensitive substance.

One. important feature of the relays shown herein is the tube-like form oi the thermoseusitive substance E, whereby this substance is exposed to a very large proportion of the heat emitted by the filament H.

Another important feature of my invention is the provision of the two terminal plugs 8 and 8 which are integral with the body of the relay. The primary or controlling circuit with which the heating element H is to be connected will include a socket designed to receive the plug 8, and the secondary or controlled circuit in which the electrodes l0 and 11 are to be included will include a socket designed to receive the plug 8. This construction greatly facilitates the insertion of the'relay in the apparatus with which it is associated, as well as the removal of the relay therefrom. Although the plugs which I have illustrated herein are of the screw type, it is obvious that plugs of any other suitable type, such, for example, as the bayonet plug, may be substituted therefor.

Relays embodying my invention are well adapted for use in rallwa si aling systerns of the type illustrat an claimed in my co-pending application for Letters Patent of the United States filed on the 16th day of April, 1921, Serial No. 461,783, for railway signaling, although they are not limittflfito this particular use.

,Altli'ough I have herein shown and described only certain forms of relays embodyrious changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A relay comprising two spaced electrodes. a therino-sensitive substance between said electrodes, and a heating element for varying the temperature of said substance within limits determined by voltage applied.

2. A relay comprising two tube-like electrodes one within the other, a thermo-sensitive substance between said. electrodes, and a heating element located within the inner electrode.

3. A relay comprising a bulb provided with two terminal plugs each having two contact members, a heating element located within said bulb and having its terminals connected with the two contact members respectively of one plug, two electrodes supported by said bulb and connected respectively with the two contact members of the other plug, and a thermo-sensitivc substance located between said electrodes.

4-. A relay con'iprising a bulb provided with two terminal plugs each having two contact members, a heating element located within said bulb and having its ltl'll'lllltllr-I connected with the two contact members respectively of one plug, two electrodes mount ed within said bulb and connected respectively with the two contact members of the other lug, and a thermo-sensitive substance ocated between said electrodes.

5. A relay comprising a bulb provided with two terminal plugs each having two contact members, a heating element located within said bulb and having its terminals connected with the two contact members respectivel y of one plu two electrodes located within said bulb an connected res ctively with the two contact members of t e other plug, a thermo-sensitive substance located between said electrodes, said bulb containing a connected with the two contact members respectively of one plug, two tube-like electrodes supported by said bulb one within the other and connected respectively with the two contact members of the other plug, the

inner electrode being so constructed as to obstruct only a portion of the heat rays emitted by said heating element, and a thermosensitive substance located between said electrodes.

7. An electrical relay omprising a bulb provided with two terminal p ugs each havmg two contact members, a htmg element located within said bulb and-having its terminals connected 'with the two contact members respectively of one plug, two tube-like electrodes supported by said bulb one within the other and connected respectively with the two contact members of the other plug, the inner electrode being perforated, a thermosensitive substance interposed between said electrodes, and an auxiliary inner electrode of heat-conductive electro-conductive material located between said substance and said perforated electrode.

8. An electrical relay comprising two spaced tube-like electrodes one within the other, the inner electrode being perforated, a

thermo-sensitive substance interposed between said electrodes, and a heating element located within the inner electrode.

9. An electrical relay comprising two spaced electrodes one of which is perforated,

a thermo-sensitive substance interposed between said electrodes, and a heating element so located as to transmit heat to said substance through the perforations of the perforated electrode.

*10. An electrical relay comprising two spaced electrodes one within the other, the inner electrode being perforated, a thermosensitive substance interposedbetween said i'- electrodes, an auxiliary electrode of heatconductive electro-conductive material bc tween saidsubstance and said perforated electrode, and a heating element so located as to transmit heat rays to said substance through the perforations in said one electrode and through said auxiliary electrode.

13. A relay comprising two spaced electrodes one of which is perforated, a thermosensitive substance interposed'between said electrodes, a heating element so located as to transmit heat to sand substance through the perforations of said perforated electrode, and a as-filled bulb enclosing said electrodes aswel as said-substance and said heating element. I

14. A relay comprising two spaced electrodes one within the other, the innerelectrode being perforated, a thermo-sensitive substance interposed between said electrodes, 7 an auxiliary electrode of heat-conductive electro-conductive material between saidsubstance and said perforated electrode, a heating element so located as to transmit heat rays to said substance through the perforations in the inner electrode and through said auxiliary electrode, and a gas-filled bulb enclosing said electrodes as well as said sub- 7 stance, and said heating element.

In testimony whereof I afiix my signature.

LABS O. GRONDAHL. 

